Electric incandescent lamp made of glass tubing



Nov. 29, 1927. 1,651,287

H. MAYER ELECTRIC INCANDESCENT LAIP MADE OF GLASS TUBING Filed March 30. 1927 4 L V E y-.7.

.1 \JM'JL'AJPA'JF Patented Nov. 29, 1927.

PATENT OFFICE.

HERMANN MAYER, OI BERLIN-LICBTERFELDE-WEST, GERMANY.

ELECTRIC INCANDESGENT LAMP MADE OI GLASS TUBING.

Application filed March 80, 1927, Serial No. 179,684, and in Germany April 8, 1926.

This invention relates to incandescent lamps made of straight or bent glass tubing and used for instance in the form of letters or any other signs. In this kind of incandescent lamps as hitherto constructed, the incandescent filament is either left entirely unsupported or is supported in a manner which is diflicult to carry out in practice. This has the drawback that the incandescent filament can easily come in. contact with the inner wall of the glass tube, whereby,

cooling points are roduced which more or less affect the per ect glowing of the filament.

This drawback is overcome according to the present invention by means of a support which ensures that the incandescent filament shall be reliably supported allalong the straight or bent glass tube in which the filament is mounted. Y

According to the invention the usual helically wound filament is surrounded along its entire length by a supporting wire which is similarly helically wound and to which 2 the filament is connected by means of filament supports. The outer diameter of the helical supporting wire is such as to correspond to the inner diameter of the glass tube, so that when it is inserted therein, it

will owing to its elasticity, firmly abut against the inner wall of the tube.

This form of support makes it entirely impossible for parts of the filament to come in contact with the glass wall, more especially in thecase of bent tubular lamps, such as for instance the bent parts of certain letters, e. g. the letter 0. At such points of contact the turns of the helical filament would not glow owing to the heat conduction of the glass wall, so that the whole of the tubular lamp may cease to glow or the letter may become illegible.

The filament supports are insulated from the supporting hehx in a known manner by means of glass The invention is illustrated, b way of example, in the accompanying rawings, as applied to the letter P.

Fig. 1 shows a glass tube bent in a known manner into the form of the letter P. V

Fig. 2 shows, on an enlarged scale, the improved supporting helix together with the filament helix, filament supports and glass beads.

Fig. 3 is an elevation of the bent tube with the supporting helix and filament helix in position, whilst Fig. 4 illustrates certain details on an enlarged scale.

The supporting helix 2 surrounding the incandescent filament 1 abuts against the straight and bent parts of the inner wall of the glass tube and the incandescent helix '1 is supported by the filament supports 5 which are secured for this purpose to the supporting helix 2 by means of glass heads 3. Preferably also the supporting helix 2 is subdivided into parts insulated from one another by means of glass heads 4 in order thereby to provide a double insulation.

The filament helix supported in the manner above referred to is simply pulled through the straight or bent glass tube, for instance letter-shaped tubes, and the tube is then provided with electric leads, evacuated and sealed up.

What I claim is An electric incandescent lamp made of glass tubing and comprising in combination with a helical incandescent filament, a helical support surrounding the helical incandescent filament and abutting with its outer surface against the inner wall of the glass tubing, filament supports for supporting the filament within the supporting helix centrally and means for insulating the said fila ment supports from the supporting helix.

In testimony whereof I have signed my name to this specification.

HERMANN MAYER. 

